Fix nonexistent variables in ItemReceivedResponse

When creating an NCIP ItemReceivedResponse message, nonexistent
variables were being referenced, resulting in warnings and empty
values for the following elements in ResponseHeader:

FromAgencyId/UniqueAgencyId/Scheme
ToAgencyId/UniqueAgencyId/Scheme
ToAgencyId/UniqueAgencyId/Value

This commit populates the variables $faidScheme, $taidScheme, and
$taidValie in a manner similar to other locations in the code,
silencing the warnings and causing the elements in question to
contain data.

Signed-off-by: Jeff Godin <jgodin@tadl.org>
use strict;

Having eliminated a number of issues with nonexistent variables being
referenced, we can now enable the "use strict" pragma.

Signed-off-by: Jeff Godin <jgodin@tadl.org>